The invention relates to an original-affixing device for affixing printing originals onto scanning cylinders for drum scanners.
Drum scanners have a scanning cylinder whereon the originals to be scanned are clamped before being scanned. Because this clamping operation on the drum scanner itself is awkward and time-consuming, these scanners are constructed so that the scanning cylinder is removable, which offers the advantage that complementing the cylinders with the originals can be performed outside the scanner, and that, depending upon the size of the originals or the type of originals, different scanning cylinders with different diameters and lengths can be used. These cylinders are complemented with the desired originals in the make-ready work before scanning takes place.
Conventionally, the originals to be scanned are mounted on the scanning cylinder manually with the aid of adhesive strips. According to the prior art, devices for simplifying and facilitating this operation have also become known heretofore. The European Published and Prosecuted Patent Application (EP-A) 0 521 311 describes a flexible frame comprising a lower and an upper plastic film, between which the original to be scanned is laid. The thickness of the plastic films is selected so as to avoid the occurrence of Newton rings, which otherwise would be disruptive during the scanning of the original. Further devices for clamping and holding sheet material on rotating drums have become known heretofore. In U.S. Pat. No. 5,324,023, a clamping device is described which holds sheet material on a drum, the holding force being further reinforced by centrifugal force during rapid rotation of the drum. The published International PCT Patent Application WO 91/03120 describes a device for automatically clamping and unclamping film material on a recording drum, having a guide surface, a pressure roller, a lifting device and a drive for transporting the film material. The film material is held on the drum by vacuum suction holes. U.S. Pat. No. 5,329,301 describes a clamping and holding device for film material on a recording drum, wherein a number of rows of vacuum suction holes are provided on the drum surface. When the material is being clamped on the cylinder, the rows of suction holes are connected in succession to a vacuum pump the instant that they are covered by the material. Film material having different formats is thereby clamped on smoothly and without creases, even if the printing material wraps only partly around the drum.
Devices for affixing originals to be scanned on a removable scanning cylinder have likewise become known heretofore, for example the original-affixing device xe2x80x9cChromaMount P 320xe2x80x9d from the firm Rudolf Hell GmbH, Siemenswall, D-24107 Kiel, Germany, order number 04071654. This device serves for affixing originals or mounting films at a correct angle on scanning cylinders. In this appliance, the scanning cylinder lies in a holder which is countersunk in a trough provided in a work table. An illumination arm serves for internally illuminating the cylinder in order to detect contamination or Newton""s rings on the cylinder or on the original. The illumination arm can be displaced axially into a left-hand end position outside the cylinder in order to change the cylinders, and in this way releases the cylinder. Provided in the trough of the work table is a roller block for accommodating the cylinders, the roller block being adjustable manually to the various cylinder sizes. The cylinders are interchanged by simply clicking the roller shaft out or in, respectively, on the roller block. Also provided is an original platform for accommodating the original before it is affixed or mounted, it being possible for the platform to be set against the cylinder surface by an adjusting wheel, the adjustment being required to be matched to the different cylinder diameters. In order to clamp the originals on, a freewheeling brake for braking the cylinder rotation is provided and serves for fixing the cylinder, that is, when the brake is set, the scanning cylinder is rotatable during the clamping operation only in one direction, i.e., in the direction of rotation of the clamping operation, but not, however, in the opposite direction. The purpose thereof is that, during the clamping of the original, the latter can be subjected to tension during the rotation of the cylinder, so that the original rests smoothly on the cylinder. It is therefore possible for the original to be held taut manually, counter to the direction of rotation of the cylinder, during the clamping operation. Also provided is a pivotable pressure roller, by which the original is pressed against the cylinder during the clamping operation. The pressure roller is interchangeable for the different cylinders, respectively. In order to remove the cylinder, the pressure roller, which is fixed to a swinging arm, can be folded upwardly.
Because speed or rapidity, i.e., simple operation of such devices, is of considerable importance during the make-ready work, manual adjustments, in particular, of the roller block here, setting of the original platform to the respective cylinder diameter, engaging the freewheeling brake, and interchanging and adjusting the pressure roller are hindrances.
It is accordingly an object of the invention to provide an original-affixing device which is of relatively simple operation and, consequently, has an optimum operating speed.
With the foregoing and other objects in view, there is provided, in accordance with the invention, an original-affixing device for affixing an original onto a scanning cylinder for a drum scanner, comprising a typewriter-like housing for accommodating and securing individual components of the device, the housing having a front, a rear and a lateral region, the housing, in the front region thereof, being provided with a movable original table whereon an original is clampable, and in the lateral region thereof, provided with two arms articulatedly connected therein and being slidable on guides for bringing the table to the scanning cylinder, the housing, in the rear region thereof, being provided with a trough extending in a longitudinal direction, the trough being open at the top for accommodating the scanning cylinder, the trough being of such construction as to be able to accommodate, respectively, one of two cylinders of different diameter, and further comprising a pressure roller extending parallel to the scanning cylinder and serving for pressing the original onto the scanning cylinder during a clamping process of the original, the pressure roller being fixed to two curved swinging arms articulatedly connected to the rear region of the housing and matching the shape of the housing.
In accordance with another feature of the invention, the arms, at lower ends thereof, by which they are guidable in the housing, are provided with two guide pins spaced a distance from one another and guidable, respectively, in coulisses.
In accordance with a further feature of the invention, the coulisses are arranged within the housing so that the original table is liftable and simultaneously displaceable in a direction to the scanning cylinder by an engagement of the pins in the coulisses, the coulisses having a course beginning in a lower part of the housing, extending obliquely upwardly in a direction to the cylinder and, via a dead center, falling again in a direction to the lower part of the housing.
In accordance with an added feature of the invention, the arms at the sides of the original table have two handles.
In accordance with an additional feature of the invention, the arms have two handles at the sides of the original table, and the original table is displaceable within the coulisses manually via the handles, the original table being liftable and being pullable forwardly so as to assume a latched position wherein the scanning cylinder is respectively insertable into and removable from the trough, and, alternatively, the original table, due to being lifted and being pushed rearwardly, and overcoming the dead center of the coulisses and being lowered in the direction to the lower part of the housing, assuming a position within the coulisses wherein the original table rests on the respective scanning cylinder.
In accordance with yet another feature of the invention, the two cylinders are a cylinder of smaller diameter and a cylinder of larger diameter, the device including, within and at the ends of the trough, two roller pairs for the cylinder of smaller diameter, and two roller pairs for the cylinder of larger diameter, the respective cylinders resting on the roller pairs, respectively.
In accordance with yet a further feature of the invention, the larger-diameter cylinder is shorter than the smaller-diameter cylinder.
In accordance with yet an added feature of the invention, the roller pairs for the cylinder of larger diameter are arranged at the ends of the trough underneath the roller pairs for the cylinder of smaller diameter, mounting supports for the roller pairs for the cylinder of larger diameter at the two opposite ends of the trough being spaced a smaller distance from one another, corresponding to the length of the larger cylinder.
In accordance with yet an additional feature of the invention, the larger-diameter cylinder has a length which corresponds to the length of the smaller-diameter cylinder.
In accordance with an alternative feature of the invention, the larger-diameter cylinder has a length which is greater than the length of the smaller-diameter cylinder.
In accordance with still another feature of the invention, the larger-diameter cylinder has a length at least equal to the length of the smaller-diameter cylinder, and an annular recess is formed at that end of the trough at which the open end of the larger-diameter cylinder is located, the open end of the larger-diameter cylinder being able to be pushed into the annular recess, the annular recess being of such width that the open end of the larger-diameter cylinder is movable freely within the annular recess.
In accordance with still a further feature of the invention, the original-affixing device includes, at the rear side of the housing, two curved swinging arms matching the curvature of the housing, an exchangeable pressure roller fixed to upper ends of the swinging arms, the pressure roller being alternatively lowerable onto the surface of the cylinder and pivotable rearwardly out of the region of the trough, respectively, by the swinging arms.
In accordance with still an added feature of the invention, the pressure roller has a mounting support constructed so that the pressure roller is freewheelingly rotatable in a direction wherein the cylinder is rotated during clamping, and is blocked in the direction of rotation opposite thereto.
In accordance with a concomitant feature of the invention, the original-affixing device includes an illuminated magnifier fixed above the scanning cylinder on the rear side of the housing, so that the region of the scanning cylinder wherein the original is to be affixed is thereby displayable in magnified form.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an original-affixing device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.